JPH02122422A - Optical disk device - Google Patents

Abstract

PURPOSE:To prevent the destruction of each constitution due to an abnormal situation by supervising the occurrence of the abnormal situation in which a tracking servo does not function, and stopping the operation of the respective parts around an optical disk and an optical head at the time of occurrence. CONSTITUTION:In the abnormal situation such as an external shock applied onto the optical disk device, although a focusing servo 11 normally functions, a case, where a tracking servo 14 does not normally function, that is, a tracking error signal is not of a direct current and has frequencies higher to some extent (for example, 200kHz), occurs. Then, a tracking abnormality supervising circuit 21 to supervise the frequency of the tracking error signal is provided, and when the frequency of the tracking error signal is increased, all the servos are stopped. Thus, the burning of the tracking coil, the burning of a motor 6 coil, the damage of an optical disk 1, and the damage of an objective lens can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc device, and is particularly suitable for application to a structure that protects an optical head and various parts around an optical disc from abnormal situations such as external shocks. .

[Prior Art] In an optical disk device, focusing servo and tracking servo are applied during recording and reproduction so that a laser beam is irradiated with a beam spot of a predetermined diameter and onto a predetermined track. Therefore, even if there is slight vertical movement or radial variation in the irradiation position, recording and reproducing operations can be performed appropriately.

However, when an external impact is applied to the optical disc device, the recording/reproducing area at the periphery moves up and down in small increments because the optical disc is supported at the center. In this case, the focusing error signal becomes a high-frequency, high-level signal, and the control signal applied to the focusing coil also becomes a high-frequency, high-level signal. As a result, the focusing coil may be burnt out, and the objective lens, which is moved up and down for focus control, and the optical disk may be damaged.

Therefore, conventionally, the focusing error signal is monitored, and if the focusing servo deviates to the extent that it cannot servo properly, the focusing servo and the
The tracking servo, the slider servo for moving the optical head in the radial direction, the spindle servo for stably rotating the optical disk, etc. were also stopped to protect each part.

[Problems to be Solved by the Invention] Incidentally, depending on external shocks, vibrations in the radial direction may also occur due to a fitting error between the center hole of the optical disk and the rotating shaft, depending on the chucking mechanism of the optical disk.
Furthermore, vibrations in the radial direction may also occur due to vibrations of the optical slider itself on which the optical head is mounted. Further, when the optical head is stopped after a search operation, the optical slider may vibrate depending on the mechanical resonance frequency, etc., and the optical head may vibrate in the radial direction.

In this case, the tracking servo deviates so much that it cannot serve properly.

Therefore, the conventional structure that protects the optical head and various parts around the optical disk only when the focusing servo is significantly deviated is insufficient, and there is a risk that this may occur if the focusing servo is functioning but the tracking servo is significantly deviated. However, it is not possible to prevent burnout of the tracking coil, damage to the optical disk, damage to the objective lens, etc.

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide an optical disc device that can protect the optical head and various parts around the optical disc even if the tracking servo is significantly deviated.

[Means for Solving the Problem] In order to solve the problem, the present invention includes a tracking servo circuit that performs servo operation in the radial direction of the optical disc so that a laser beam spot is irradiated onto a predetermined track on the optical disc. In an optical disk device, a tracking error signal is received from a tracking servo circuit, and based on the frequency of this tracking error signal, the occurrence of an abnormal state in which the tracking servo does not function is detected, and the operation of at least the optical disk and various parts around the optical head is stopped. A tracking abnormality monitoring circuit has been installed to prevent

[Operation] In an abnormal situation such as when an external impact is applied to the optical disc device, the focusing servo functions normally, but the tracking servo does not function normally, that is, the tracking error signal is not direct current, There are cases where the frequency is relatively high (for example, 200 kHz).

Therefore, we have installed a tracking abnormality monitoring circuit that monitors the frequency of the tracking error signal to prevent damage to the optical disk and components around the optical head due to inappropriate servo when the wave number of the tracking error signal becomes high. The operation of each component around the optical head is now stopped.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the overall configuration of this embodiment. An optical head section 2 (concept including an optical slider) is provided adjacent to the optical disk 1. A recording signal is applied to the optical head section 2 from a recording circuit 3. The recording circuit 3 modulates recording data and applies it to the optical head section 2 under the control of a control circuit 4 having a microcomputer configuration, and the optical head section 2 irradiates the optical disc 1 with a laser beam that is intermittent in accordance with the recording signal. It is made to do.

The signal picked up by the optical head section 2 during reproduction is given to a reproduction circuit 5. Under the control of the control circuit 4, the reproducing circuit 5 demodulates the pickup signal to the original tape and outputs the demodulated signal.

Furthermore, various servos are executed under the control of the control circuit 4.

A drive signal is applied to the motor 6 that rotates the optical disk 1 from the spindle servo recess 287 via the switch circuit 8, and the motor 6 rotates in response to this. An encoder 9 is connected to the rotation shaft of the motor 6, and the encoder 9 feeds back rotation speed information of the motor 6 to the spindle servo circuit 7. The spindle servo circuit 7 is
Based on the rotation speed command from the control circuit 4 and the rotation speed information fed back, the motor 6 is driven so that the optical disc 1 rotates at a predetermined speed.

A light reception signal for focusing received by, for example, a four-part light receiving element in the optical head section 2 is given to a focusing servo circuit 11 via a switch circuit 10. The focusing servo circuit 11 detects a focusing error signal under the control of the control circuit 4 and provides a control signal to the optical head unit 2 via the switch circuit 12 so that the beam spot diameter on the optical disc 1 is appropriate. For example, the objective lens position is varied in the vertical direction.

Further, the light reception signal for I/racking received by the light receiving element in the optical head section 2 is given to the tracking servo circuit E@14 via the switch circuit 13. The tracking servo circuit 14 detects a tracking error signal under the control of the control circuit 4 and sends a control signal to the optical head unit 2 via the switch circuit 15 so that a beam spot is irradiated onto a predetermined track of the optical disc 1. For example, the position of the entire optical pickup is varied in the radial direction of the optical disc 1.

The slider servo circuit 16 is given track number information etc. to be accessed from the control circuit 4, and the slider servo circuit 16 uses this information and the tracking servo circuit 1.
A control signal for determining the position of the optical head section 2 is formed based on the tracking error signal given from the optical head section 4, and is applied to the optical head section 2 via the switch circuit 17. variable in the radial direction.

In addition to the above configuration, this embodiment is provided with a configuration to protect each part from an abnormal situation where the focusing servo or the tracking servo does not function.

A focusing error signal detected by the focusing servo circuit 1-1 is provided to a focusing abnormality monitoring circuit 20. The focusing error monitoring circuit 20 monitors this focusing error signal and outputs a protection signal if the focusing servo is no longer effective.

The tracking error signal detected by the tracking servo circuit 14 is applied to a tracking abnormality monitoring circuit 21 whose detailed configuration is shown in FIG. The tracking abnormality monitoring circuit 21 monitors this tracking error signal and outputs a protection signal when the tracking servo is no longer effective.

The protection signal output from the focusing abnormality monitoring circuit 20 and/or the tracking abnormality monitoring circuit 21 in this way is transmitted to the switch circuit 8.10.1 via the OR circuit 22.
2.13.15 and 17 are given as open command signals. When the protection signal is output in this way, all the speedo operations are stopped, and the optical head section 2, motor 6, optical disk 1, etc. are protected.

Next, the tracking abnormality monitoring circuit 21 will be described in detail with reference to FIG.

Here, the racking error signal given to this tracking error monitoring circuit 21 is a signal at a DC level when the servo is functioning properly, but when an abnormal situation such as a shock occurs, the racking error signal is applied to the optical disc. When the optical head 1 vibrates in the radial direction or the optical head 2 on the irradiation side vibrates in the radial direction, the signal becomes an alternating current signal. Therefore, the tracking abnormality monitoring circuit 21 monitors abnormalities based on the frequency of the input tracking error signal.

The waveform shaping circuit 30 pulse-shapes the input tracking error signal and supplies it to the frequency/voltage conversion circuit 31 .

The frequency/voltage conversion circuit 31 supplies a DC voltage signal corresponding to the frequency of this pulse signal to a comparator circuit 32 having an analog configuration. A reference voltage signal is given to the comparator circuit 32 from a reference value setting volume 33.
The input DC voltage signal and this reference voltage signal are compared in magnitude, and if the input DC voltage signal is large, a protection signal is output to each switch circuit.

Therefore, according to the above-described embodiment, all servos are stopped in the event of an abnormal situation such as an external shock that prevents the tracking servo from functioning properly. It is possible to prevent burnout, damage to the optical disc 1, and damage to the objective lens.

FIG. 3 shows a second example of the tracking abnormality monitoring circuit 21. In this second example, the racking error signal TR (see FIG. 4 (A)) is transmitted to the waveform shaping circuit 40.
After shaping the pulses via the gate signal generation circuit 41, the counter circuit 4 is connected to the counter circuit 4 via the gate circuit 42 whose opening and closing are controlled by the gate signal GT (see FIG. 4(B)) generated by the gate signal generation circuit 41.
3, and this counter circuit 43 receives a pulse signal PT(
Refer to FIG. 4(C)), the count value is compared with a reference count value by a digital comparator circuit 44 to determine an abnormal situation, and the input count value is is larger than the reference count value, a protection signal is output to each switch circuit.

Therefore, even with the tracking error monitoring circuit of this second example, when the frequency of the tracking error signal becomes high enough to prevent the tracking servo from functioning, all the switch circuits can be opened and all the servos can be stopped. , the optical head section 2, motor 6, etc. can be protected from such abnormal situations.

In addition, in the above-mentioned embodiment, when an abnormal situation occurs,
Although the system shown here stops the operation of each part around the optical disk and optical head, the protection signal is given to the control circuit 4 as a reset signal to stop the operation of other components such as the control circuit, modulation circuit, demodulation circuit, etc. You can do it like this.

In addition, in the above-described embodiment, an optical disk device that can perform both recording and playback processing (for example, a magneto-optical disk device) is shown; The present invention can also be applied to devices.

[Effects of the Invention] As described above, according to the present invention, the occurrence of an abnormal situation in which the tracking servo does not function is monitored, and when this occurs, the operation of each part around the optical disk and optical head is stopped. It is possible to prevent each component from being damaged due to an abnormal situation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of an optical disk device according to the present invention, FIG. 2 is a block diagram showing a first example of the tracking abnormality monitoring circuit, and FIG. 3 is a second example of the tracking abnormality monitoring circuit. FIG. 4 is a block diagram showing signal waveforms of various parts of a second example of the tracking abnormality monitoring circuit. DESCRIPTION OF SYMBOLS 1... Optical disc, 2... Optical head part, 3... Recording circuit, 4... Control circuit, 5... Demodulation circuit, 6...
・Motor, 7... Spindle servo circuit, 8.10.
12.13.15.17...Switch circuit, 11...
- Focusing servo circuit, 14... Tracking servo circuit, 16... Slider servo circuit, 20...
- Focusing abnormality monitoring circuit, 21... Tracking abnormality monitoring circuit, 22... OR circuit, 30... Waveform shaping circuit, 31... Frequency/voltage conversion circuit, 32...
- Comparator circuit, 33... Volume for setting reference value.

Claims (3)

[Claims] (1) In an optical disc device equipped with a tracking servo circuit that performs servo operation in the radial direction of the optical disc so that a laser beam spot is irradiated on a predetermined track, a tracking error signal is acquired from the tracking servo circuit, and the frequency of this tracking error signal is What is claimed is: 1. An optical disk device comprising: a tracking abnormality monitoring circuit that detects the occurrence of an abnormal situation in which a tracking servo does not function based on the above, and stops operation of at least various parts around the optical disk and the optical head. (2) The tracking abnormality monitoring circuit is configured with a frequency/voltage conversion circuit that converts the frequency of the tracking error signal into a voltage, and a comparator circuit that compares the converted voltage signal with a reference voltage signal. The optical disc device according to claim 1, wherein: (3) The tracking abnormality monitoring circuit compares the count value with a reference count value with a waveform shaping circuit that converts the tracking error signal into a pulse signal and a counter circuit that counts pulse signals formed for a predetermined period. 2. The optical disc device according to claim 1, further comprising a comparator circuit.